Digital processors have gained acceptance in a wide variety of applications. Such processors are very complex devices and as such require the existence of a specific starting state in order to properly execute the program instructions and commands for which they are designed. In general, at initial turn on, the specific starting state is supplied by a power on "reset in" signal generated by logically "ANDing" one or more of the power supply voltages for the processor itself.
For most processors, such as the 8085A microprocessor manufactured by the Intel Corporation, the "reset in" signal must be in the form of a pulse of specific duration depending on the internal characteristics of the processor. Since, after the initial turn on, the power supplies which generate the "reset in" signal normally remain on, the processor itself, or auxiliary circuitry, provides a "reset out" signal which can be used to logically remove the "reset in" signal after the necessary time has elapsed.
For a wide variety of reasons, such as random static discharges, power supply start-up problems, or temporary short circuiting of a data bus by repair personnel, the processor hardware can be temporarily disturbed. Unfortunately, once such a "soft" failure occurs the processor may be unable to resume orderly operation once the disturbance has passed. Such a condition is often referred to as "getting lost" since the processor is unable to resume normal operation unless the power to the entire processor is manually turned off, then back on in order to generate a new "reset in" signal.